How do you lock or unlock the toilet from the outside?

The correct process to lock or unlock the toilet from the outside involves lifting the lavatory sign and sliding the latch across. This design ensures that crew members can quickly and effectively manage the toilet's accessibility during flights for safety and operational efficiency.

When the lavatory sign is lifted, it reveals a mechanism that allows the latch to be moved, providing direct control over the lock without needing specialized tools or a key. This method is both intuitive and designed for ease of use, allowing for rapid response in situations where timely access or security may be critical.

The other methods listed do not pertain to this aircraft's design for managing the lavatory lock system and therefore do not provide the functionality needed in this context.